Folate has potential to cause harm

EDITOR,--Nicholas J Wald and Carol Bower favour a population strategy rather than a selective strategy to prevent 1000 neural tube defects annually in the United Kingdom, with compulsory fortification of flour with folic acid.1 They could perhaps have strengthened their case by referring to other potential benefits of their proposal--for example, in mental health, especially in psychiatric and geriatric populations.2 Instead, however, they rather undermine their case by inaccurately minimising the disadvantages of their policy.

Their statement that “even in large doses folic acid has not been shown to cause harm” should not pass unchallenged. Although they acknowledge that folic acid may mask the anaemia of pernicious anaemia, they fail to emphasise that it may precipitate neurological complications in this context, as colleagues and I have shown.3 This can occur in the absence of anaemia, macrocytosis, or even a low serum vitamin B-12 concentration. The authors suggest that the problem of masking pernicious anaemia could be resolved by education, but apparently they do not favour a selective educational approach to prevent neural tube defects.

The risk that seizures may increase in patients with epilepsy4 is rather casually dismissed by the suggestion that higher doses of antiepileptic drugs might be needed, as if this in itself did not carry any risk.

A wider and more detailed consideration of all the advantages and disadvantages of the authors' proposals would be appropriate.